MAG58's DOHC L28 Build Log

[MAG58]

1 Fast Z,

I PM'd Mack, Hopefully I will get some information soon, though searching through his posts, I found that the Cylinder head he was looking at was the older M110 engine that was out in the mid-80's. This was a 2 valve head and the M104 was a radical re-design with a fitting bore spacing and head bolt arrangement. The M104 was a re-design of the M103 head, which was an SOHC head. The motor can be found on W-124 and W-202 sedan's and coupes between 1990 (3.0-24 designation) and 1991-1997 (2.8 & 3.2 displacement) starting with the old Bosch mechanical injection Merc was so known for swapping to the electronic injected examples which is the head I have.

 

As far as head flow, I don't have numbers, but just comparing exhaust between this motor and an RB, i have no doubt that the exhaust on this head will out flow a 26 head lift for lift with stock castings.

[MAG58]

FYI this is the M110 that Mack said would NOT fit, which has been a rumor since way before I was born...

 

 

 

And this is a Picture of the M104 engine in bay, which is the head that I have.

 

Note, the front of this engine has a dizzy on the exhaust camshaft, this is a 3.0-24 engine. My M104 3.2 head does not have this as it went to a DIS setup when they switched out the mech. Injection for the Bosch Electronic.

[Mack]

yeah, I never found anything newer than late 80s for mercedes engines in the junkyard. It had always been the rumor that the mid 70s models were the ones that fit. Which is not true. VERY good work, MAG! Ive been to the Upullit in indy (my friend lives in noblesville) and they get crazy new cars in there!! they had 2 G35s when I was there!!!

 

And TonyD, are you saying that YOU knew about this head fitting on an L serties block?

[HowlerMonkey]

This also begs the question of putting the entire mercedes engine into a nissan though that brings up other powertrain fitment issues.

[MAG58]

While I was looking at the merc engine, I will say this, It's front sump, and you'd have to cut the cross member or the firewall since it has a chain drive oil pump that sits below the front of the engine. It's actually similar to the BMW V12 design that a member here has documented switching to dry sump to rectify the situation. Though it's a stout engine, since it has that cool symbol, parts are pricey and factory non-auto cars are rare. fwiw, I just looked up the price of a factory new piston (just one) and it was 374 bucks

 

I'm just trying to find a viable head option for the L series. If I was going to do an entire engine swap there are hundreds of Cheaper, faster, simpler, and probably more efficient options out there.

 

Bob

[HowlerMonkey]

True....the replacement parts are expensive.

 

That might be why there are at least 6 locally in u-pull yards in west palm.

 

My car requries a front sump engine....Hmmm.....

 

Great work and I'm really surprised at the bore centers being where they are.

[MAG58]

I've got a few more pics for you guys to see what this looks like before the block goes off to get bored and milled for the bigger head bolts...

 

Here's what it looks like with the two respective front covers in place :

 

And this is what the old, blown HG looks like sitting atop the L28 block

[/img]

 

Also of note, I just measured the F54/P79 combo in my Z currently, and the new head with the valve cover is just over an inch shorter on the short side of the head and slightly taller (maybe 1/4'') on the tall side of the head, so it should fit with no problem in the Z! Note this is was measured from the flange at the oil pan to the top of the valve covers at the center of each.

 

Let me know what you think!

Bob

[Careless]

have to say...this is pretty cool!

[1 fast z]

WHen I built my head, the timing system and cams was by far the most complicated and time consuming when compared to the actuall head. Getting the head together and everything lined up was actually the easy part. What is the aftermarket support for these motors? As far as cams, valves, etc? Is this a solid cam head? When you take the block and head to the machine shop, ask them to flow bench the head. Looks can be VERY deciving. Did you know that a stock P90 head flows about the same as a 7mgte toyota head?

[MONGO510]

Outstanding research Mag58!!! You da Man!!

 

John

[MAG58]

1 fast Z,

 

The timing system here is going to be complicated as expected, however it runs a timing chain of the same width between the rows and pitch as the L chain even though the tooth number is different, as two L series timing gears atop that head would make reasonable chain angles and follwers basically unfeasable. I plan on going soon to get the M104 timing sprocket to see how close it is to the L series crank snout journal. I know for sure the bottom timing cover will be modified by using an external water pump along with the aforementioned planned re-jacket. This will allow me to use a wider (space between the chains) tensioner and use less radical angles at the top end of the head. And I knew the 7M head doesn't flow that great, especially when you put a non-crossflow Z head next to it. I do however know that these engines have been and are raced in germany to great success. AMG, Barabus, and Schrick do or have at one time made cams for this car, along with springs, although the stock springs can be spun to 8500 without much problem. The lifters are hydraulic as pictured and I checked, are produced by the same mfg as the Audi 20V motor and those lifters can be seen in high rpm (8500+) race motors in europe and here using these lifters, though there are a few companies that are making a solid lifter conversion for these should you feel that you absolutely have to run SLA's. As far as flow goes, I know looks can be deceiving, but this casting is used in the German touring car series and is VERY competitive against 400hp NA BMW S motors. I cant yet provide with confidence the exact details on this motor. Benzworld along with a few german sites (first time i've ever used my high school and college german classes, take that education system!) have a wealth of information on these heads.

 

 

Hope this helps, don't mean to step on anyone's toes.

 

Bob

[e_racer1999]

Wow, this is GREAT information. I too would be interested in seeing the flow numbers. I have a sneaking suspicion that the FranKAnstein head is going to have better flow characteristics, but this is still an excellent starting platform that is a better alternative to those of us that don't have the machining prowess that Blake Machining does

[Tony D]

Do I know it fits, or did I know just what MAG has discovered that bore spacing, etc is damn close enough to warrant further investigation.

 

The question WAS NOT 'know this fits' --- the question responded to was 'how has this head slipped by us all for this long?' or some permutation thereof...

 

It did most decidedly NOT 'slip by' me for sure. I've chucked the DOHC conversion as too much effort for too little gain (er... if any, I still have yet to see ANY DOHC conversion outperform the properly prepared Non-Crossflow L-Head.)

 

If someone is saying this engine will make 1200HP in Turbocharged form at less than 9000 rpms, and 30PSI of boost (oh, and last 26hours on the dyno at that level)...

 

Then I'll be marginally interested for a street car. For the racing class I'm entered into, it's disallowed, so why bother?

 

That sum up my stance? I'm not threadjacking this, nor am I denigrating any effort made towards this end. I'm just stating why I personally have decided it's not worth the effort in my case.

 

As an exercise in machining or to say "I did it" is eminently all the justification it needs under any condition. Hell, "Just Because" is good enough for me to do most things. But in this case, I just don't see tangible gains being had above what the good old L-Series has already proven it can do for about $2500 in head work, TOPS!

[Daeron]

Wow, you got me hooked! I can't say that there is a single I-6 cylinder head I have looked at in the junkyard without thinking "Gee, I wonder.... Bah, I'll never have the opportunity to even think about it."

[woldson]

What will the c/r be?

[MAG58]

Sorry to cause all the animosity between you guys, the entire object of this project is to create an L series that is more livable on the roads than a big, slobbering, loapy, ported L head while still providing relatively comparable performance. This was never meant to be a fire-breathing monster, as I'm very sure an LS1, RB, JZ, SBC, and a whole bunch of other motors do that perfectly fine. This is more of an "it's never really been done before with this set-up" kind of forte into this realm. As far as flow goes, finding a shop that does GOOD head welding and has a decent flow-bench reputation is seeming to be the really difficult part. A few german sites list the intake at roughly the same flow as the KA head lift for lift and the exhaust MAYBE a little more. This may be way off, it was just my 2AM german translation and conversion from that pesky metric system. I don't intend this to flow better.

As far as cost goes I do not plan on throwing lots and lots of money at this and as I go you will see the budgeted options I have to make this work without sinking an arm, leg, and a first born into it.

 

That all said, the CR on the 2.8 was 10:1 using flat-tops, so with factory dished turbo pistons it should provide a very streetable turbo CR in the mid 9's, I will CC the heads for sure though

 

Bob

[Daeron]

You aren't "causing" any animosity; this is a subject that has been open to a great deal of speculation and BSing, so you have to understand you are treading water in a sensitive area.. Tony was clarifying his statement from earlier, and his last post was directed against the forces of Vagueness and Imprecise Language everywhere. Clear, honest, factual communication is the only method humans have of transferring ideas from one to another, and the members of this forum try to have utmost respect for that. That being the case, TonyD could NOT let such a huge blanket statement as "how did we all let this escape our notice for so long?!?!" slip by him, nor can I blame him. My reaction to reading that was "Speak for yourself!! I haven't ruled out anything I haven't seen on a block, and that ain't anything!"

 

 

Semantics are NOT trivial!!

[Tony D]

Daeron pegged my intent exactly. I'm not upset or showing animosity. I'd seen the head in the past, and played around. But it never rated more than an 'emph...if I had the time this might be interesting' kind of thought. Especially since for the money spent, you can get the same HP out of the non-crossflow head. My driving point is the non-crossflow head is good for operation at 9000+ rpms, and the horsepower availabe at that level is pretty good as mentioned. So I've always needed a quantification of improvement over the L-Head. Sure, the TC24B-1 O.S. Giken Head is a nice whiz-bang underhood goody for a show...but I'd like a performance bump to make the $$$ outlay worthwhile.

[1 fast z]

A Crossflow DOHC that flows more and has more valve area will ALWAYS make more power tony, Plain and simple. Just because you were part of a team of guys that took a 2.0 liter motor to 10,000 with a non crossflow head, doesnt mean that was the best. I gurantee you a dohc head on that same block would make more power, and have more area under the torque curve, and HP curve.

[Gollum]

Oh come on guys, there's no reason to get heated about any of this (I know it's not there yet, I'm just saying I don't want it to go there).

 

We can ALL agree that this is an INTERESTING project to say the least, and if well documented might even be ATTAINABLE to some degree for others that have access to a machine shop, and willing to take the time to fabricate the parts needed. The KA swap, though extremely impressive, I think scares a lot of people and in reality isn't practical for anyone other than someone who works at a machine shop and has extensive experience and knowledge of cyinder heads, oiling and cooling systems.

 

I for one, will be more than happy to subscribe to this thread and wait with bated breath. Not that I'd truly consider doing it, but I find it so amazing to tell my car buddies "hey, guess what some guy with way too much time did to a Z!" I just love showing off now nuts some Z car guys can get and support any addiction this heavy to the car hobby.